Could Spider Silk Stop a Moving Train?

Spiderman really could have stopped that train from falling, so long as his silk resembled that produced by the Darwin's bark spider

Spider-Man’s silk could have stopped a moving train—if his silk resembled the stuff produced by the Darwin’s bark spider, which lives in Madagascar and builds enormous 80-foot wide webs.

A team from the University of Leicester set out to test the reality of this hypothetical hero move from the second Spider-Man movie, Wired reports:

First, the team calculated how much four R160 New York City subway cars — packed with a total of 984 people — would weigh (about 200,000 kilograms, or roughly 10 Atlas V rockets). Then, they calculated how fast the train was going (24 meters per second, or about 53 miles per hour) and how much resistance the track would have offered as it charged forward (negligible). From there, they could work out how much force the webbing would have needed to exert upon the train to stop it: about 300,000 Newtons, or about 12 times the amount of force exerted by a large American alligator as its jaws snap shut.

Figures in hand, the team considered the way trains, webs and anchor buildings would interact geometrically and how much tensile strength a line of web would need in order to hold up a train without snapping.

After crunching the numbers, they found that Spider-Man could indeed have saved that train from plummeting off the track. Spiders such as the Darwin’s black spider produce silk with strength values of 1.5 to 12 gigapascals. Scale those values to a human-sized spindle of silk and web, and the calculations add up to amazing, train-stopping abilities.